Telephonic transmitting apparatus



(No Model.)

J. T. GUTHRIE.

TELEPHONIG TRANSMITTING APPARATUS.

' Patented Mar. 23, 1886.

N PETERS. Pholn-Lilhographen \Vashingmn, D. C.

A UNITED STATES PATENT OFFICE.

JAMES T. GUTHRIE, OF LEESBURG, OHIO.

TELEPHONIC TRANSMITTING APPARATUS.

SPECIFICATION forming part of Letters Patent No. 338,263, dated March 23, 1886,

(No model.)

To all whom, it may concern.-

Be it known thatI, JAMES T. GUTHRIE, of Leesburg, in the county of Highland and State of Ohio, have invented certain new and useful Improvements in Telephonic Transmitting, Calling, and Switching Apparatus; and I do hereby declare the iollowing to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to improved telephonic transmitting apparatus having in view the following objects: First, to secure currents of high inductive power for the operation of telephonic receiving-instruments, it being well known that the induced currents now ordinarily used, while having high tension, have very low magnetizing capacity; secondly, to

reduce the cost of telephonic transmitters.

In the accomplishment of these objects my invention consists in certain novel constructions and combinations of devices,which will be fully understood from the following particular description in connection with the accompanying drawings, in which Figure 1 is a front view of a telephone subscribers station apparatus comprising my improvements. Fig. 2is a view of the transmit ter with its door open. Fig. 3 is a vertical section on the line a" x of Fig. 2.

The casing 15 of my improved transmitter T is provided with a hinged door, t,at the center of which is formed a concave depression having at its center an opening at t about one half inch in diameter. Behind this opening is the center of the transmitter-diaphragm D, which is a disk of thin sheet metal (preferably ferrotype-plate) about two and a half-inches in diameter. The margin of this diaphragm is covered on both sides with india-rubber, and itis laid flatwise against the back of the door, and there secured by a ring, a, of metal attached to the door by screws. Above the diaphragm and its securing-ring a small bar, J, of carbon is screwed firmly to the non-conducting door, and attached to and depending from this carbon bar is a short metallic arm, F, from an intermediate point of which, on the side next to the diaphragm, a thin stripspring, f, of metal extends downward to the center of the diaphragm, and is provided witha cross-arm, f, one end of which bears lightly against the diaphragm at its center, and the other projects outward and comes in contact with a block, Q, of plumbago, which has its lower end hinged to the door below the diaphragm;

and is held upright by a light spring-arm, g, r

on a post, and having a stiff short arm, 9*, the end of which is swiveled. to the tip ofa thumb-screw, 9 passing through the door and accessible from without for adj usting-the presscross-arm f. A small screw, f, in arm F serves. to adjust the spring f. The block Q of plumbago and the' cross-arm f are the electrodes, the varying pressure between which regulates the character of the electrical impulses which fiow upon the line, the variation of such pressure resulting from movements of the diaphragm in response to sound-undulations projected against it. One end of the carbon bar J is connected by a short wire, j, with a metal plate, 12, let into the rear upper margin of the door, and a similar plate, 12, is connected by a wire, j, with the metal bracket q, in which the plumbago block Q is hinged. These two plates 1) o are arranged to press against two strip-springs, '1) 0 which project from the bindingposts 19 1) on the top of the casing 1, so that when the door is closed electrical connection from'the two electrodes will be made to said binding-posts, and at the same time the door may be freely opened. Upon the top of the casing is also another bindingpost, p, the use of which will presently appear.

In the battery-casing G is to be located a battery, preferably of the class known as bi chromate-of-potassium batteries. From one pole of this battery a wire, w, leads to earth,or connects with the line leading to another station, and from the other pole a wire, 10, leads to the circuit-breaker D and connects with a metal finger-spring, d, the opposite end portion of which bears upon the top of a metal post, (1. Transversely under the spring-finger d is mounted a small revolving shaft, (1 provided at one end with a crank, (1 intermedi ately and under the tip of the spring-finger d. It has two wings, d* d, extended so far radially that when the shaft is revolved these wings will successively strike the tip of the spring and raise it out of contact with post d. From this post d a win-2,10, leads to a bindu're of the block of plumbago against the ing-post, 12 which is connected with one terminal of the bellmagnet, (not shown,) the other terminal of which is connected to a post, 10 from which a wire, 19*, leads to the bindingpost p on the transmitter-case. From this post the spring 2; makes connection to plate 12, from whence the circuit through the electrodes and to post 11 has been already explained. From post p the current leads through the receiving-telephone R to post p, and thence off over the line-wire L, leading toward the cen- V tral station, or through an intermediate station.

I do not confine myself to the precise construction and arrangement of parts as heretofore described, and as shown in my drawings, but reserve to myself the right to vary the same in any manner for the better carrying out of myinvention without departing from the true spirit and scope thereof,

The calling and switching devices herein described and shown are not claimed, as they will form the subject-matter of a separate application.

Having fully described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. In a transmitting-telephone, the combinati'on,with the diaphragm, of the carbon bar, the metal arm and spring metallic electrode supported thereby,and the plumbago electrode 30 hearing against said metallic electrode, essentially as set forth.

2. In a transmitting-telephone, the combination of a diaphragm, a vibrating metallic electrode in contact with said diaphragm, and 35 a hinged plumbago electrode, Q, resting against the outer end of the metallic electrode, sub stantially as shown and described.

3. The combination, with the diaphragm, the metallic electrode, and the hinged plum- 4o bago electrode, of the adjustable spring-arm arranged to press the pl umbago electrode against the metallic electrode, substantially as described.

In testimony whereof I have signed this 5 specification in the presence of two subscribing witnesses.

JAMES T. GUTHRIE.

Witnesses:

W. T. GOVAN, L. L. SEoRIsT. 

